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Post subject: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Mon Nov 04, 2019 8:19 pm
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Aspiring Musician
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I think it IS the processor overheating that causes the volume drops ! Tim mentioned it as did TorpidAnima in the thread he just started. As i stated i had reasons to logically believe thats probably not the case but now i think i may be eating my words. Here's why. It started cutting out again just now and i put a fan on the back. A little 10" house fan on high speed and withing about 1 minute it stopped dropping out. And heres what is even further proof....stopped GRADUALLY. That is, the dropouts are not always the same. At times the dropout portion is 1/2 as loud as it is when the volume jumps back up. Other times it's only slightly lower. And theres every level in between. When it started just now it was at it's worse, and when i put the fan on it i kept hitting a chord and it gradually changed till the dropout was hardly any lower and then finally gone altogether and working normally.

So thats got to be it. It's never done that before and the way it gradually came back is proof. So i am going to open her up and put a heat sink on the cpu. I have thermal grease i ave from putting PCs together so i'll use that and just push a heat sink onto the cpu and then maybe use silicone to hold it on. I just have to have a look and see how to do it but thats my first thought. If that doesn't do it i'll see if i can find a fan that won't leak noise into the circuit. Keep and eye on this thread and i will post results once i've done it and i've played it long enough.


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Fender Play November 2019
Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Mon Nov 04, 2019 8:50 pm
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Pulled the chassis and theres already a heat sink. As u can see there is another chip next to it so maybe that one is the issue, who knows. But i guess a fan is in order. Anyone like Tim wanna tell me what spec to look for in a tiny fan that will ensure no circuit noise? I assume any PC fan would be good.

By the way, one other reason it made so little sense it would be a heat issue is we just ended a summer of 90-105 degree days and while the issue did crop up now and then, it wasn't till the weather cooled that it started happening daily rather then mothly or less ! Kinda odd.

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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Tue Nov 05, 2019 7:28 am
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Professional Musician
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oczad wrote:
Anyone like Tim wanna tell me what spec to look for in a tiny fan that will ensure no circuit noise? I assume any PC fan would be good.

I'm not an amp tech, but I'm a computer tech. IMO, yes a PC fan is most likely the best you can do if the fan must be powered by the amp. Speaking of power - how are you going to add a power header for the fan?


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Tue Nov 05, 2019 7:34 am
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I'll have to probe the PSU for the proper voltage or create a seperate 5 or 12v node for it. Worse case, put a wall wart in it or in the back of the amp. The latter would be the easiest way.


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Tue Nov 05, 2019 8:54 am
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If confirmed, that would mean Fender sold a whole lot of amps that have a design flaw. :shock: Will be interesting to see how this plays out.


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Tue Nov 05, 2019 10:08 am
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That would be a LOOOOOOOONG ways from the first time for fender or most any other brand for that matter.


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Thu Nov 07, 2019 8:55 pm
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To pinpoint your problem, get a can of freeze spray and poke around with it. When you find a sensitive area, you can flatten a Q-tip with pliers and freeze it. Apply the Q-tip to individual components to find the culprit.
You can use a hair dryer or embossing blow tool to reheat the board to cycle it through. Then freeze again.
Look for bad solder, bad through holes and bad components.


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Thu Nov 07, 2019 9:09 pm
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I know, i've used that for years to find bad IC's and such, but this isn't a bad component IMO, just a heat issue that goes away just by pointing a house fan on the back. And being so indirect and not remotely as cold, just air, chances are freezing a component in the amp will stop the issue even if the component is even just near the culprit. So an internal PC fan will no doubt be a 100% fix judging by how quickly a fan just pointed at the back panel stopped it. In other words, it seems like it's right on the edge where it would take next to nothing to keep it under that like. A tiny 2" fan will likely do the trick.


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Fri Nov 08, 2019 6:35 pm
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I was quite sure it was overheating related and could likely be fixed without the need of a fan btw. Just need to find a beefier heatsink with better dissipation and use quality thermal compound and it would likely fix the issue regardless of outside temps.


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Fri Nov 08, 2019 8:58 pm
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yeah but It's very cheaply made. The HS is glued on and very fragile. It would likely kill the chip if i did that. A fan will work 100% given that just having a fan pointed at the back panel for a minute stopped the issue. So a tiny little fan is all it would take. I suppose i could expand the stock HS with some "wings", but best just to stick a fan in it.


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Sat Nov 09, 2019 8:46 am
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True but an oscillating fan could introduce unwanted noise into the circuit. Which depending on fan speed could be a bad high pitch. That is if you are planning on trying to use power from amp power stage and mount it internally. So I would test positioning of the fan well before committing to its final position. Would also make sure the fans cables are shielded well. The current heat sink is quite wimpy and they are not too hard to replace honestly just have to take your time doing it. Though I am not sure its worth the effort or risk.

Have you verified the issue to be overheating for sure on your end as well? Mine hasn't dropped out once since I starting using a small oscillating fan after I made my other post. The one I have is a clip on fan for inside your vehicle. I grabbed mine from Advance Auto (similar to Part No. AC845) years ago and modified it with a wall wart to run off wall AC (was car plug prior). The clamp works great and can clamp it right on the back panel of the amp cab and face it up. Just a thought and doesn't require any modding or risks to amp. Likely could find one that doesn't require modding and works on AC out of the box. Quick search I found item B000U9V47E on Amazon but would want a black one instead of white.

Good luck and take lots of pics and vids of your project to share with us pretty please :)


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Sat Nov 09, 2019 12:07 pm
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Yeah, thats why i have yet to do it. Been researching what to look for in order to do this w/o noise. They use a zillion fans in a desktop and you can play music thru your PC with no noise at all so it can be done. I just don't know what things to consider other then the obvious. I may just mount a wall wart in the back of the amp and run the cable to the fan from there. Maybe a brushless fan may also be a good idea.
\
As to verifying the heat issue, as i said in the original post above a fan on the back caused the issue to stop within a minute which it has never done in the past. Always had to reboot. So yeas, i consider that verified, especially since i could hear the dropout get less and less gradually till it was 100% gone over the minute i had the fan on it.

I've been thinking about the HS tho and i may just get in there and add some bigger wings to it if it seems doable. It's such a random issue that doen't happen a heck of a lot that i think it's very much on the line between not enough cooling and enough to never dropout. Might just take a tiny bit more to be reliable.


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Sat Nov 09, 2019 12:35 pm
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Ya know, come to think of it, that little house fan causes noise in my amp even without having anything in common other then both being plugged into the same mains socket. So chances are i may have to just thru hops to get a fan to work w/o circuit noise. So i'm going to try adding some aluminum to the current HS. I'll update if and when i do this and see what the result is.


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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Sat Nov 09, 2019 1:00 pm
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oczad wrote:
I may just mount a wall wart in the back of the amp and run the cable to the fan from there. Maybe a brushless fan may also be a good idea.

Brushless will probably be harder to deal with, as they run high-frequency controllers to switch the field coils.
A conventional AC fan fed from the mains will be the most quiet electrically.
There's a few 80mm x 38mm low-speed fans on Amazon that will move a lot of air pretty quietly. If electrical noise is an issue, the longer 50/60hz wavelength would be easier to build a simple screen cage to shield without blocking airflow. These plug directly into the mains socket.
Brushless would require a much finer mesh, and the speed controller produces audible noise from the switching.

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Post subject: Re: Well i'll be da##ed ! (dropout issue possible fix)
Posted: Sat Nov 09, 2019 1:22 pm
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Well then maybe i'll look at ac. That would certainly make it much easier. But first i am going to see about adding some mass to the HS. If that doesn't work i'll check out an ac fan, tho not sure i have ever seen a very small one.


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